These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
The films contain examples of:
Adaptation Displacement: You can imagine how many people have even heard of the original books. In fact, there are a good 12 within the series. The final book, Bernard Into Battle, was made not too long after the first movie.
"Message Montage" from the sequel (which incorporates "R-E-S-C-U-E, Rescue Aid Society" - The Rescuers Down Under has no songs, unusually for Disney).
The score stands on its own. It's beautiful.
The song that seems to be Medusa's theme; you know the one. Also, the song that plays during the escape sequence at the end of the film.
The Shelby Flint songs from the first film, along with the instrumental theme, "Faith is a Bluebird", and, of course, the "Rescue Aid Society Theme".
Evenrude's theme in the first film.
Complete Monster: Percival McLeach is a sick and twisted poacher. He starts by kidnapping Cody, a child who confronts him about his poaching, and then McLeach tricks the authorities into thinking Cody is dead, by throwing Cody's backpack to the crocodiles. From there he tosses knives at Cody, locks him in one of the cramped cages he keeps the animals he's captured in, and to top it all off, ties Cody to a crane and lowers him into another river filled with crocodiles, only to raise him back up — then almost does it again just to toy with him. When the power on the halftrack goes out, stopping him from lowering Cody, McLeach takes out a gun and shoots the rope holding him above the river. Oh, and it is heavily implied that the reason he is a poacher is specifically because he enjoys hurting and killing animals.
Evil Is Cool: McLeach was worse than Medusa as far as his actual actions go, but it was easier to dismiss him since, due to George C. Scott obviously having a ton of fun voicing him, he came off as being "cooler." Plus, he's got a friggin halftrack. That's badass no matter who you are.
Germans Love "The Rescuers": According to famed Disney animators Frank Thomas and Ollie Johnston in their book "Disney Animation and the Illusion of Life", when The Rescuers was released in Germany, it became the highest grossing picture of all time in that country.
Magnificent Bastard: McLeach. When threats and violence don't loosen Cody's tongue, McLeach hatches a plan to trick Cody into leading him to Marahute by claiming she was shot by another hunter and then releasing him, anticipating that Cody will go to her nest to protect the eggs. He is proven correct, and he successfully catches Marahute as a result.
Joanna has a minor, but hilarious, example of being one when she manages to steal and eat all of the eggs McLeach was going to use to make an omelet through a series of clever tricks and fake-outs.
Moral Event Horizon: McLeach and Medusa each have various moments per character that are potential candidates for this, although you'll hear different answers from different people on which moment whichever character actually crossed it.
Medusa goes from kidnapping an orphan girl named Penny so as to use her to find a diamond in a cave beneath a well to encouraging Snoops to be harsher when Penny doesn't find it to personally making Penny look for the diamond in the cave even though this actually puts Penny's life in danger. Then when Penny gets the diamond and Medusa takes it, Medusa holds Snoops AND Penny at gunpoint to deter them from taking it.
McLeach goes from kidnapping Cody (the young boy who confronted McLeach's poaching) to tricking the authorities into thinking Cody is dead by throwing his backpack to the crocodiles to trying to coerce an eagle's whereabouts out of Cody by throwing sharp knives close to his head to locking Cody up in the same cages he uses for captured animals...but the most likely moment for Moral Event Horizon comes in the form of having Cody hanging from a rope tied to a crane, then lowering Cody into crocodile-infested waters and raised back out again, only to try and lower him in again, this time permanently. McLeach's intent was to "tie up" the last "loose end" by eliminating the only human witness to his preceding crimes in a way that would look like an accident — he even laughs about how the rangers will now find Cody's body at Croc Falls, exactly where they thought he was killed. But he just wanted to torture Cody first for the fun of it, apparently.
Nightmare Fuel: In Down Under, McLeach's psychologically torturing a boy... actually torturing a little boy...
What the hell were the nurse mice going to do to Wilbur with that chainsaw?
The Scrappy: Ironically, Medusa is probably more hateable than McLeach even though her villainy is arguably less extreme because Medusa is cruel in a more realistic way, IE, we've all occasionally had moments where we've felt worthless, and watching Medusa exploit that was too much for many.
Padding: The entire scene with Cody in the cages with the animals. It doesn't affect the story, none of the characters during it are met again and the whole scene was rather pointless as nothing was accomplished.
Almost necessary padding just to get it to feature-length; the movie runs a scant 77 minutes.